Air classifier assembly

ABSTRACT

Air classifier assembly for sizing particulate material includes a sizing chamber, a rotary distributor plate located in a lower portion of the sizing chamber for flinging particulate material supplied to the plate into the sizing chamber, a substantially cylindrical fine-particle separating chamber coaxially surrounding the sizing chamber and communicating therewith through an opening in the upper portion thereof, ventilating means located in the separating chamber for drawing into the separating chamber fine particles from the particulate material in the sizing chamber, ventilating means and a fine-material separator located externally to the separating chamber, the externally located ventilating means having a suction line connected to the fine-material separator and therethrough to an upper portion of the separating chamber and a compression line connected tangentially to the separating chamber.

United States Patent 1191 Jager 1 May 22, 1973 54] AIR CLASSIFIERASSEMBLY 1,457,110 5 1923 Gay...; .1 ..209 139 Inventor: Heinz g BochumGermany 3,095,369 6/1963 Jager ..209/l39 [73] Assignee: WEDAG WestfaliaDinnendahl Primary Examiner-Frank W. Lutter Groppel Aktiengesellschait,Assistant Examiner-Robert Halper Bochum, Germany Attorney-Curt M. Avery,Arthur E. Wilfond, Herbert [22] Filed: Jan. 20, 1970 L. Lerner andDaniel J. Tick [21] Appl. No.: 4,280 [57] ABSTRACT Air classifierassembly for sizing particulate material [30] Foreign ApplicationPriority D t includes a sizing chamber, a rotary distributor platelocated in a lower portion of the sizing chamber for Jan. 25, 1969Germany ..P 19 03 743.5 particulate material pp i to the Plate into thesizing chamber, a substantially cylindrical fine-par- [52] US. Cl...209/l39 A, 209/144 ticle separating chamber coaxial), surrounding the[5 1] Int. Cl. ..B07b 7/10 ing chamber and communicating therewiththrough an [58] Field of Search 209/ 139, 138, 133, opening in the upperportion th f ventilating 209/140-1421 144, 130, 137 means located in theseparating chamber for drawing into the separating chamber fineparticles from the 1 References Cited particulate material in the sizingchamber, ventilating means and a fine-material separator locatedexternally UNITED STATES PATENTS to the separating chamber, theexternally located ven- 2,966,625 12/1960 Jager ..209/139 A il ing meanshaving a suction line connected to the 2,790,550 4/1957 Doyle ..209/l44fine-material separator and therethrough to an upper 17,853 7/1857Zimmerman... ..209l139 X portion of the separating chamber and acompression 880,242 2/ 1908 Robinson ..209/ 139 X line connectedtangentially to the separating chamber. 580,145 4/1897 Raymond ..209/l39X 1,367,636 2/1921 Sturtevant ..209/ 139 A 2 Claims, 2 Drawing Figures pa fi 8 2 ii 5 J 1,1 l 1 1 1} i Q 6 1 1 1 4 g, n 10 \i Patented May 22,1973 3,734,287

INVENTOR AIR CLASSIFIER ASSEMBLY My invention relates to air classifierassembly and more particularly to such device having a distributor platedelivery and an internally disposed ventilating fan and a sizing chambercoaxially surrounded by a dust or fine-particle separating chamber.

In known construction types of such air classifiers, refined dust passesinto the fine-particle separating chamber after it leaves the sizingchamber. The air current entraining the dust or fine particles travelsupwardly in the fine-particle separating chamber along a helical path,the dust or fine being hurled toward the outer wall of the fine-particleseparating chamber and thereby dropping downwardly along the wall to thefine-material outlet at the bottom of the fine-particle separatingchamber. However, since the fine particles are not completely separatedin the fine-particle separating chamber, a fraction thereof is returnedwith the circulating air flow through a vane or jalousy structure intothe sizing chamber. Enrichment of the fines in the sizing chamber thenoccurs, sharply reducing the throughput efficiency as well as theseparating or classifying action of the device with respect to the areaof the sizing chamber.

It is accordingly an object of my invention to provide air classifierwhich avoids the foregoing disadvantages of the heretofore knownclassifiers of this general type and which more particularly avoidsreduction in the throughput efficiency as well as the classifying actionof the device.

With the foregoing and other objects in view I provide, in accordancewith my invention, an air classifier assembly for sizing particulatematerial comprising a sizing chamber, a rotary distributor plate locatedin a lower portion of the sizing chamber and defining an annular spacetherewith for flinging particulate material supplied to the rotarydistributor plate into the sizing chamber,a substantially cylindricalfine-particle separating chamber coaxially surrounding the sizingchamber and communicating therewith through an opening in the upperportion thereof, ventilating means located in the fine-particleseparating chamber for drawing into the separating chamber fineparticles from the particulate material in the sizing chamber,ventilating means and a fine-material separator located externally tothe fine-particle separating chamber, the externally located ventilatingmeans having a suction line connected to the fine-material separator andtherethrough to an upper portion of the fine particle-separating chamberand a compression line connected tangentially to the fine-particleseparating chamber. In this way, fine particles are additionallyseparated continuously from part of the particle-laden sizing air whichis returned to the fine-particle separating chamber.

In accordance with a further feature of my invention, means are providedfor returning the sizing air from which the fine particles have beenseparated to the sizing chamber in a tangential direction theretowhereby an additional ascending rotational movement of the sizing air isproduced in the sizing chamber.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin air classifier assembly, it is nevertheless not intended to belimited to the details shown, since various modifications and structuralchanges may be made therein without departing from the spirit of theinvention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings, in which:

FIG. 1 is an elevational view, partly in section, of an air classifierassembly in accordance with my invention; and

FIG. 2 is a top plan view of FIG. 1.

Referring now to the drawings, there is shown in the figures aclassifier housing 1 provided with a supply hopper 2 extendingdownwardly, as shown in FIG. 1, to a location above a distributor plate3 rotatable by a drive shaft 4 which is driven by a suitable drivetransmission located at the top of the classifier housing 1. Aventilating fan wheel 5 is suitably mounted on the distributor plate 3,for example, as shown in FIG. 1 so as to be rotatable therewith. Asizing chamber 6 is disposed within the classifier housing 1 and isspaced therefrom so as to define a fine-particle separating chamber 7coaxially surrounding the sizing chamber 6. The fan wheel 5 is locatedin the upper part of the fineparticle separating chamber 7 above anopening at the top of the sizing chamber 6 providing communicationbetween the latter and the fine-particle separating chamber 7. Anexternally located fine-particle separator 9, in the form of a cyclone,for example, is connected by a tube 15 tangentially to a fine-particleand air mixture outlet formed in an upper portion of the fine-particleseparating chamber 7 and is also connected by a suction line 8 to thesuction side of an externally disposed ventilating fan or blower 10. Areturn line 11 extends from the compression side of the externallydisposed ventilating fan 10 and connected tangentially with thefine-particle separator chamber 7 of the classifier.

The operation of the air classifier of my invention is as follows.Particulate material is supplied in the direction of the arrow at thetop of FIG. 1 through the hopper 2 onto the rotary distributor plate 3and is flung thereby in radial direction into the sizing chamber 6, thecoarse particles thereby falling into a collecting chamber 12 anddischarged through an outlet 13. Due to the suction created by therotating ventilating fan wheel 5, the fine-particle fraction of thematerial located in the sizing chamber 6 is withdrawn from the openingat the top of the sizing chamber 6 and blown into the fine-particleseparator chamber 7. The fines are accordingly flung by centrifugalforces against the inner surface of the classifier housing 1, slidedownwardly along the surface and discharge through an outlet 14 at thebottom of the classifier. Part of the sizing air flow is sucked out ofthe fine-particle separating chamber 7 by the externally located bloweror ventilating fan 10 through the tube 15 into the fine-materialseparator 9 wherein most of the fines entrained in the sizing air floware precipitated and discharged from an outlet at the bottom thereof asshown by the associated arrow. The sizing air flow thus freed in thefine-material separator 9 of the fine-particles entrained thereby thenpasses through the ventilating fan 10 and is returned by the compressionline 11 to the classifier.

Although in the embodiment shown in FIG. 1 the compression line 11 isconnected tangentially to the fine-particle separating chamber 7, it mayalso be desireable in accordance with the invention to extend the line11 so that it passes through the fine-particle sepa rating chamber 7 andconnects tangentially with the sizing chamber 6.

In the assembly according to my invention a further advantage isobtained in that two different end products can be produced, namely aproduct from the classifier per se and a second product from thefinematerial separator 9 by varying the degree of separation ofclassifying in the fine-material separator 9 in response to a suitablevariation in the rotary speed of the external ventilating fan 10.

I claim:

1. Air classifier assembly for sizing particulate material comprising asizing chamber, a rotary distributor plate located in a lower portion ofsaid sizing chamber and defining an annular space therewith for flingingparticulate material supplied to said rotary distributor plate into saidsizing chamber, a substantially cylindrical fine-particle separatingchamber coaxially surrounding said sizing chamber and communicatingtherewith through an opening in the upper portion thereof, ventilatingmeans located in the fine-particle separating chamber for drawing intosaid separating chamber fine particles from the particulate material insaid sizing chamber, said fine-particle separating chamher having anoutlet at an upper portion thereof for venting therefrom a mixture offine particles and air produced in said separating chamber, ventilatingmeans and at least one fine-particle separator located externally tosaid fine-particle separating chamber, said externally locatedventilating means having a suction line connected to said externallylocated fine-particle separator and therethrough to said outlet andtangentially to said fine-particle separating chamber at said upperportion thereof and having a compression line connected tangentially tosaid fine-particle separating chamber at a lower portion thereof.

2. Air classifier assembly according to claim 1 wherein said externallylocated ventilating means comprises a fan having means for varying therotary speed thereof so as to vary the degree of separation effected bysaid fine-particle separator.

1. Air classifier assembly for sizing particulate material comprising asizing chamber, a rotary distributor plate located in a lower portion ofsaid sizing chamber and defining an annular space therewith for flingingparticulate material supplied to said rotary distributor plate into saidsizing chamber, a substantially cylindrical fine-particle separatingchamber coaxially surrounding said sizing chamber and communicatingtherewith through an opening in the upper portion thereof, ventilatingmeans located in the fine-particle separating chamber for drawing intosaid separating chamber fine particles from the particulate material insaid sizing chamber, said fine-particle separating chamber having anoutlet at an upper portion thereof for venting therefrom a mixture offine particles and air produced in said separating chamber, ventilatingmeans and at least one fine-particle separator located externally tosaid fine-particle separating chamber, said externally locatedventilating means having a suction line connected to said externallylocated fine-particle separator and therethrough to said outlet andtangentially to said fine-particle separating chamber at said upperportion thereof , and having a compression line connected tangentiallyto said fine-particle separating chamber at a lower portion thereof. 2.Air classifier assembly according to claim 1 wherein said externallylocated ventilating means comprises a fan having means for varying therotary speed thereof so as to vary the degree of separation effected bysaid fine-particle separator.